A three-color exercise
For a first experiment, choose a simple motif and three pencils: one light, one medium, and one dark color. On a separate sheet, make three swatches of each using light, moderate, and slightly firmer pressure. Then use the light color for larger areas, the medium color for details, and the dark color for a few accents. This is just a starting point; if you prefer another combination, change it.
Choose a page that invites you in
Look through a few illustrations and stop at one that catches your eye. It does not have to be the most detailed. A drawing with open spaces can be just as interesting as a scene full of tiny elements.
Try a small palette
Pick three or four colors you like together. Try them on a separate sheet, then decide where to use them. If you are using markers, test how the paper handles the ink and protect the next page with a spare sheet.
You do not have to finish today
A page can stay on the table until tomorrow. Change the palette, leave white spaces, or return to a detail later. The lovely part is that you choose how it looks and how much time to give it.